Graphitization Furnace

Abstract

A gravity-fed reactor comprising: an inner tube defining an interior; a heating assembly circumferentially surrounding at least a portion of the inner tube, the heating assembly having at least one heating element configured to apply heat to the inner tube; an outer shell defining at least a lower portion of a gas path circumferentially surrounding the heating assembly; a gravity-fed reactor; a supply structure configured to receive a raw material, the supply structure defining a raw material receiving space in communication with the interior of the inner tube of the reactor; and a furnace comprising the supply structure, wherein the interior of the inner tube of the reactor is fluidly isolated from the heating assembly and the gas path.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims priority to both U.S. Provisional Application Nos. 63 / 354,521 and 63 / 354,526, filed on June 22, 2022, and both U.S. Provisional Application Nos. 63 / 479,573 and 63 / 479,571, filed on January 12, 2023. Each of these priority applications is incorporated herein by reference.

Background Art

[0002] The current supply of graphite in the United States is less than 10 metric kilotons. Considering the growing electric vehicle market among other end - uses, the report suggests that the demand for graphite will increase to 30 kilotons by 2030. Most of the existing anode - grade graphite is produced by processes with several drawbacks. The most common thermal processes involve the use of Acheson - type furnaces. These furnaces are not only very dangerous due to the high risk of electric shock, but also batch - limited, labor - and energy - intensive. In a typical Acheson - type process, approximately 30% of the graphitizable raw materials are often discarded as landfill waste.

[0003] Processes for making natural or hybrid natural / synthetic graphite have similar drawbacks. A typical acid leaching process for preparing natural graphite requires chemical consumables and can cause significant pollution if the waste stream is not properly diverted to a water treatment plant. Batch induction furnaces and continuous heat treatment processes are energy - intensive and typically require expensive and inefficient power technologies and frequent component replacements. There is a need for an improved method for graphitizing materials suitable for some end - uses as anode - grade graphite materials.

Summary of the Invention

[0004] The present disclosure relates to a graphite furnace and a method of using a furnace to efficiently and cost-effectively graphitize feedstock materials using heat treatment.

[0005] An embodiment of the disclosed furnace is a gravity-fed reactor comprising: (a) an inner tube defining an interior; (b) a heating assembly circumferentially surrounding at least a portion of the inner tube, the heating assembly having at least one heating element configured to apply heat to the inner tube; (c) an outer shell defining at least a lower portion of a gas path circumferentially surrounding the heating assembly; and (d) a feed structure configured to receive feedstock, the feed structure defining a feedstock receiving space in communication with the interior of the inner tube of the reactor. In one embodiment, the interior of the inner tube of the reactor is fluidly isolated from the heating assembly and the gas path.

[0006] Also described, for example, is a method of using a furnace to convert graphitizable feedstock to graphite at high temperature. The resulting graphite can be used in a variety of applications including as electrodes for electric vehicles.

[0007] The foregoing summary, as well as the following description of the disclosure, will be better understood when read in conjunction with the accompanying drawings. For purposes of illustration of the disclosure, the drawings illustrate some, but not all, alternative embodiments. The disclosure is not limited to the exact arrangements and instrumentalities shown. The following figures, which are incorporated herein and form a part hereof, assist in explaining the principles of the disclosure.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0021] The following exemplary embodiments illustrate the present disclosure. The scope of the present disclosure and the scope of the claims are not limited by the scope of the following embodiments.

[0022] One exemplary embodiment of a graphite furnace is illustrated in FIG. 1. The graphite furnace 10 includes a gravity-feed reactor 20. The gravity-feed reactor 20 can be designed to graphitize a graphitizable material at a very high temperature, for example, 2000 - 3000 °C. The graphitizable material enters the gravity-feed reactor 20 through a supply structure 30 that defines a raw material receiving space (40) in communication with the interior of an inner tube (not shown in FIG. 1) of the gravity-feed reactor 20. The raw material is transferred to the raw material structure 30 through a raw material transfer system 50 that is in fluid communication with the raw material receiving space 40 of the raw material structure 30.

[0023] An embodiment of the raw material transfer system 50 is designed to receive the raw material, evacuate an internal space defined by at least a portion of the raw material transfer system 50, and refill the internal space with an inert gas such as argon. This ensures that ambient air does not enter the raw material receiving space (40), thereby ensuring that the atmosphere inside the inner tube of the gravity-feed reactor 20 remains inert during graphitization.

[0024] Various mechanisms are contemplated for supplying graphitizable material to the raw material transfer system 50. In the embodiment illustrated in FIG. 1, the graphitizable material is supplied into the raw material transfer system 50 from a pneumatic tube 52 that draws raw material from a raw material reservoir 54. In various embodiments, the pneumatic tube 52 and the raw material reservoir 54 are substantially sealed or sealed from the ambient air. The advantage of the pneumatic tube 52 and the raw material reservoir 54 is that the inlet supply system is not screw-fed.

[0025] During operation, the graphitization furnace 10 can operate in a continuous temperature regime. In some embodiments, the material can be graphitized at a rate of 15 kg / hour or more, and the graphitized material exits the graphitization furnace 10 continuously. In some embodiments, the raw material can be introduced into the graphitization furnace 10 in either a continuous or batch-wise manner. In one embodiment, for example, the graphitized material can exit the graphitization furnace 10 while simultaneously graphitizable material is being supplied into the graphitization furnace 10.

[0026] The embodiment illustrated in FIG. 1 includes an aftercooler assembly 60 configured to cool the graphitized material exiting the gravity-fed reactor 20. The aftercooler assembly 60 can include an outlet 70 that can be tapered in a downward direction such that the diameter of the outlet 70 decreases in some embodiments. In some embodiments, the aftercooler assembly 60 is configured to cool the graphitized material to about 800°C.

[0027] The embodiment of FIG. 1 also includes a conveyor assembly 80 in communication with the outlet 70 of the aftercooler assembly 60. In some embodiments, the conveyor assembly 80 is designed to further cool the graphitized material to about 50°C. In the embodiment illustrated in FIG. 1, the conveyor assembly 80 is generally in fluid communication with a product collection system 90 designed to collect and contain the graphitized product. In some embodiments, the product collection system 90 includes a HEPA-certified filter to ensure that the graphitized product does not enter the external atmosphere.

[0028] The embodiment of FIG. 1 also shows a furnace programmable logic controller and a power supply 95. The advantages of the embodiment of FIG. 1 are that, in addition to providing lower power losses with shorter low-voltage power lines, it enables a much shorter processing time compared to existing systems. Finally, the embodiment of FIG. 1 provides a graphitized system that has an unexpectedly high power factor when compared to systems operating today, enables more efficient use of electricity, and consequently reduces the cost per kWh.

[0029] In comparison, existing Acheson furnaces require manual loading and unloading of powder into the graphite crucible, manual loading and unloading of the crucible onto the furnace stack, and long processing times per batch (on the order of 2 to 3 weeks per time unit in the embodiment of FIG. 1). This results in high power losses, a low power factor, and consequently higher costs per kWh. Acheson furnaces also operate with large temperature gradients, leading to unpredictable quality variations. Additionally, Acheson furnaces are much less safe than the embodiment illustrated in FIG. 1.

[0030] A. Gravity-fed Reactor A more detailed view of the embodiment of FIG. 1 of the gravity-fed reactor 20 (below the supply structure 30) is shown in FIG. 2. The gravity-fed reactor 20 has an inner tube 100 that defines an interior 110. The reactor 20 also has a heating assembly 115 that circumferentially surrounds at least a portion of the inner tube 100. The heating assembly 115 has at least one heating element configured to apply heat to the inner tube 100.

[0031] In some embodiments, at least one heating element includes at least one resistive heating element. In further embodiments, at least one heating element includes a plurality of heating elements positioned to circumferentially surround at least one portion of the inner tube 100. In certain embodiments, at least one heating element includes four heating elements. In some embodiments, at least one heating element is a graphite electrode, which, when resistively heated with direct current, can allow the interior 110 to reach a temperature suitable for graphitization, such as 3000 °C or higher. In particular, for larger scale graphitization processes, other embodiments are contemplated where the heating assembly is configured to be inductively cooled.

[0032] The gravity-fed reactor 20 has an outer shell 120 that defines at least a lower portion 123 of a gas path 125 that circumferentially surrounds the heating assembly 115. In one embodiment, the outer shell 120 comprises a thermal insulation spaced radially outward from the inner tube 100. The thermal insulation can be graphite felt.

[0033] In one embodiment, the gas path 125 can be configured to receive helium, while the interior 110 of the inner tube 100 can be configured to receive argon. The advantage of this embodiment is that it can avoid the use of nitrogen throughout the reactor atmosphere, and the use of nitrogen tends to cause wear on the reactor components. Thus, in one embodiment, the interior 110 of the inner tube 100 is fluidly isolated from the heating assembly 115 and the gas path 125, which allows the interior 110 to contain an inert gas different from the inert gas occupying the gas path 125.

[0034] Due to the high temperatures required for graphitization, in some embodiments, at least a portion or all of the inner tube 100, at least the electrode portion of the heating assembly 115, and the outer shell 120 are made of graphite that can withstand the high temperatures reached in the gravity-fed reactor 20.

[0035] In one embodiment, the inner tube 100 has an upper portion 102 that is not circumferentially (circumferentially) surrounded by the heating assembly 115. In a further embodiment, the gas path 125 circumferentially (circumferentially) surrounds at least a portion of the upper portion 102 of the inner tube 100.

[0036] B. Feed Structure An embodiment of the feed structure 30 more generally illustrated in FIG. 1 is shown in FIG. 3. The feed structure 30 includes a housing 80 that defines a raw material receiving space 40 (also shown in FIG. 1) and a raw material inlet 210. The housing 80 circumferentially (circumferentially) surrounds the raw material inlet 210. The housing 80 also defines at least a portion of the upper portion 127 of the gas path 125 (see FIG. 2 showing the lower portion 123 of the gas path 125). Referring collectively to FIGS. 1-3, in one embodiment, the boundary between the upper portion 127 and the lower portion 123 of the gas path 125 is generally defined as the point where the housing 80 of the feed structure 30 and the outer shell 120 of the gravity-fed reactor 20 meet.

[0037] Referring to FIGS. 2-3, in one embodiment, at least a portion of the upper portion 127 of the gas path 125 is radially outwardly spaced from the inner tube 100 and the raw material inlet 210. In a further embodiment, the housing 80 has an inner surface 220, the raw material inlet 210 has an outer surface 225, and the furnace 10 further includes a gas receiving space (not numbered in FIG. 3) defined between the inner surface 220 of the housing 80 and the outer surface 225 of the raw material inlet 210. In one embodiment, the gas receiving space is in fluid communication with the gas path 125.

[0038] In one embodiment, referring still to FIGS. 2-3, the raw material inlet 210 has a maximum inner diameter that is larger than the diameter of the inner tube 100. Referring to FIGS. 1-3, the advantage of such a design is that during operation, the graphitizable material entering the raw material receiving space 40 of the supply structure 30 will be within the heat radiation range of the gravity-fed reactor 20, specifically, the interior 110 of the inner tube 100. As part of the graphitization process, a portion of the graphitizable material entering the furnace volatilizes within the interior 110 of the inner tube 100 (e.g., silicon, iron, etc.) and moves upward therein toward the raw material receiving space 40. Since the raw material receiving space 40 is significantly cooler than the interior 110 of the inner tube 100, those undesirable portions of the graphitizable material are effectively isolated by the graphitizable material within the raw material receiving space 40. When the graphitizable material within the raw material receiving space 40 falls by gravity into the interior 110 of the inner tube 100, the isolated portions on the graphitizable material re-evaporate and move upward again into the raw material receiving space 40.

[0039] This phenomenon enabled by the unique design of the embodiment shown in FIGS. 1-3 effectively enables the graphitizable raw material to function as a sacrificial low-temperature zone that isolates unwanted vaporized materials before they are graphitized. This consequently avoids problems associated with the re-condensation of unwanted vaporized materials on the insulation and other materials, and ultimately enables the furnace to operate continuously for a longer period, particularly compared to designs that require periodic replacement of components due to the deposition of typical conductive alloys from the graphitizable material on parts intended for insulation.

[0040] C. Raw Material Transfer System Referring to FIGS. 1 and 3, furnace 10 may include a raw material transfer system 50 that is in fluid communication with a raw material receiving space 40 of a supply structure 30. In one embodiment, the raw material transfer system 50 has at least one valve 310 configured to prevent air from entering the raw material receiving space 40. In one embodiment, the raw material transfer system 50 includes a double dump valve system that includes valve 310 in addition to supply valve 312. The double dump valve system allows graphitizable raw material to enter the raw material transfer system 50 and then may discharge ambient air and be refilled with an inert gas such as argon. This ensures that the remaining interior portion of the furnace is maintained in an inert atmosphere. Thus, in one embodiment, the raw material transfer system 50 may include a negative pressure source 320 configured to discharge air from within the raw material transfer system 50.

[0041] D. Aftercooler and Conveyor Assembly Referring to FIGS. 1, 2, and 4, furnace 10 may include an aftercooler assembly 60 configured to cool the material exiting inner tube 100 of reactor 20. For example, the aftercooler assembly 60 may include an inner tube 62 that is in fluid communication with inner tube 100 of reactor 20. In some embodiments, the inner tube of the reactor may extend along the length of the aftercooler assembly and the length of inner tube 62 of the aftercooler assembly.

[0042] The aftercooler assembly 60 may further include an outlet 70. In some optional embodiments, at least a portion of the outlet of the aftercooler assembly 60 may be tapered as it moves in a downward direction to reduce the cross-section (e.g., diameter) of the outlet 70.

[0043] Referring to FIGS. 1 and 4, in some embodiments, the furnace 10 may include a conveyor assembly 80 that communicates with an outlet 70 of the aftercooler assembly 60. The conveyor assembly 80 may move the graphitized material towards a product collection system 90. The product collection system 90 may be, for example, a container configured to store the graphitized material. In an exemplary embodiment, the container of the product collection system 90 may be a HEPA-certified collection and storage container.

[0044] Referring to FIG. 4, in some exemplary embodiments, the conveyor assembly 80 may include a screw 82 and a conveyor housing 88. The conveyor assembly 80 may have a first end 84 and an opposing second end 86. The screw 82 may be configured to rotate to convey material through the conveyor housing 88 in a direction from the first end 84 to the second end 86.

[0045] Referring to FIG. 5, in some alternative embodiments, the screw 82 may be a horizontal or inclined screw. That is, in some embodiments, the screw 82 may extend horizontally or inclined in a direction from the first end 84 to the second end 86. For example, in some embodiments, the screw 82 may form an angle with the horizontal plane of 0 degrees to about 45 degrees, or 0 degrees to about 30 degrees, or 0 degrees to about 10 degrees, or 10 degrees to about 30 degrees. In other embodiments, the screw 82 may be horizontal.

[0046] In some embodiments, the screw 82 may be a mass flow screw. Optionally, the mass flow screw may be water-cooled.

[0047] Referring to FIGS. 4 and 6, in some embodiments, screw 82 may comprise one or more threads 405 having a pitch that increases as it moves horizontally away from the reactor (e.g., from a first end 84 to a second end 86). Threads 405 may extend from the body 410 of screw 82 and define flights 412 therebetween. Flights 412 may have a sufficient depth (measured radially from the body 410 to the outer diameter of the threads to provide sufficient flow through conveyor assembly 80). For example, flights 412 may have a radial depth of at least 1 inch, at least 1.5 inches, at least 2 inches, at least 2.5 inches, at least 3 inches, or more.

[0048] Continuing to refer to FIGS. 4 and 6, in some alternative embodiments, threads 405 of screw 82 may have a diameter that increases as it moves horizontally away from the reactor. That is, threads 405 may extend radially outwardly from the axis of rotation of screw 82 with a radius. Threads 405 may gradually or incrementally increase the radius from the axis of rotation along the axis of rotation of the screw.

[0049] Referring to FIG. 4, in some alternative embodiments, the conveyor housing 88 may have an inner diameter. That is, the conveyor housing 88 may optionally have a substantially cylindrical interior. The thread 405 of the screw 82 may have a maximum diameter. In this way, the thread 405 may have a gap between the inner diameter of the conveyor housing and the maximum outer diameter of the screw 82. The gap may be less than 3 inches, or less than 2 inches, or less than 1 inch, or less than 1 / 2 inch, or less than 1 / 4 inch. By limiting this gap, unwanted flow through the conveyor 80 can be suppressed. In a further embodiment, the conveyor housing 88 and the screw 82 cooperate to define a bypass area defined by a two-dimensional surface that extends radially from the screw 405 to the inner surface of the housing along a single pitch of the thread (one 360-degree movement of the thread) including the maximum outer diameter of the screw 82. The bypass area may be less than 20, 15, 12, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 square inch.

[0050] Referring to FIGS. 7 and 8, in some alternative embodiments, the furnace 10 may include a first valve 415 positioned between the outlet 70 of the aftercooler assembly 60 and the conveyor assembly 80. The first valve 415 may be configured to control the flow rate of the material entering the conveyor assembly.

[0051] In a further embodiment, the conveyor assembly 80 may include an outlet 92. The furnace 10 may include a second valve 94 configured to control the flow rate of the material exiting the outlet of the conveyor assembly.

[0052] In some embodiments, the first valve 415 and / or the second valve 94 can be a rotary valve (FIG. 8). For example, the first valve 415 and / or the second valve 94 can include a housing and a body having a plurality of vanes (e.g., eight vanes) rotatable within the housing to measure the flow through the housing. In alternative embodiments, the first valve 415 and / or the second valve 94 can be a butterfly valve (see FIG. 4) or a knife gate.

[0053] Referring to FIG. 4, optionally, the furnace 10 can include a temperature sensor 96 (e.g., a thermocouple) that communicates with the interior of the conveyor assembly 80. The temperature sensor can be configured to determine the temperature of the graphitized material. In some optional embodiments, the temperature sensor can be configured to determine the temperature of the graphitized material at or near the outlet 92. The speed of the conveyor assembly 80 can be adjusted to control the temperature of the graphitized material exiting the outlet 92 of the conveyor assembly. In this way, the graphitized material can be sufficiently cooled to be received by the product collection system 90. In a further embodiment, the temperature sensor 64 can be provided at or near the outlet 70 of the aftercooler assembly 60. The valve 94 (FIGS. 7-8) can deliver the graphitized material to the conveyor assembly 80 after the thermocouple reaches a sufficiently low temperature (e.g., about 50° C. or less). In some embodiments, this can avoid damage to the conveyor assembly 80.

[0054] For example, the temperature sensor 96 can communicate with a computing device (e.g., a PLC). The computing device can be configured to adjust the speed of the conveyor based on the temperature measured by the temperature sensor. For example, the computing device can increase or decrease the rotational speed of the screw 82 to increase or decrease the flow through the conveyor assembly 80.

[0055] Referring to FIG. 9, in some embodiments, conveyor assembly 80 may be omitted. For example, furnace 10 may include a first valve 418 that measures the flow from the outlet 70 of aftercooler assembly 60. The first valve 418 may be a rotary valve. The first valve 418 may measure the flow into surge vessel 420. The surge vessel 420 may have an outlet 422 that communicates with container 426. In a further embodiment, a second valve 424 (e.g., a knife gate) may selectively discharge the flow from the surge vessel 420 to the container 426.

[0056] Referring to FIG. 10, in a further embodiment, aftercooler assembly 60 may include a heat exchanger 419 (e.g., a chiller) configured to remove thermal energy from the aftercooler assembly and thus the materials therein.

[0057] In some embodiments, most or all of the components of the graphitization furnace are exposed to high temperatures (e.g., 800 - 3000 °C, which can be the production of graphite).

[0058] E. Raw Materials The raw material for the graphitization furnace can be any graphitizable material. Examples include needle coke, a type of petroleum-derived coke, natural graphite, other graphite materials, carbonaceous powder (e.g., 10 - 300 microns), carbon black including carbon black having a particle size up to a few millimeters in diameter, other powdered carbon black, lignite, anthracite, certain plastics, and commercial needle pet coke. The method of using the graphitization furnace can result in graphite with high purity flakes, in some cases with a purity of 99.99% or more. The graphitized material can be used in various useful applications, including as electrodes for electric vehicles.

[0059] F. Graphite Property Evaluation Device Also described is a sampling device for characterizing a graphitized material. The sampling device is suitable for use in any embodiment of the disclosed graphitization furnace or any other graphitization reactor. Generally, the sampling device uses a fixed focal length optical alignment system for material property characterization, which can be any such system, for example, a Raman-based microscope system. In one embodiment, the disclosed graphitization reactor (or any other graphitization reactor) may further comprise an optical sampling device configured to measure the properties of the graphitized material after the material has passed through the reactor. The controller may be configured to receive an input indicative of the measured properties of the graphitized material. In a further embodiment, the controller may be configured to modify the operation of the disclosed furnace (or any other reactor) based on the measured properties of the graphitized material.

[0060] FIG. 13 illustrates one exemplary embodiment of a sampling device. The sampling device 500 generally includes a body 520 that defines a sample receiving space 530. The sample receiving space 530 may communicate with a sample collection port 540. The sample receiving space 530 may include a sample support surface 550. The sampling device 500 also includes a fixed focal length optical alignment system 560 for measuring the properties of a flow of input material, such as graphitized material from a furnace. The optical alignment system 560 may include a Raman-based system, such as a confocal Raman microscope system. The sample collection ports 540(a, b) may be configured to receive a sample from a flow of material 580 (e.g., graphitized material) and enable delivery of the sample to the sample support surface 550 within the sample receiving space 530, and the optical alignment system 560 may be configured to measure the properties of the sample (e.g., degree of graphitization by spectroscopy) when the sample is supported on the sample support surface 550.

[0061] In a further embodiment of FIG. 13, the sampling device 500 is coupled to a body 520 that defines a sample receiving space 530 and includes a sample collection tube 600 that extends outwardly from the body 520. The sample collection tube 600 may be characterized by an internal space 620 that communicates with the sample receiving space 530 of the body 520 such that the collection tube 600 communicates with or defines a sample collection port 540a. In the embodiment shown in FIG. 13, the sample collection tube 600 is selectively movable to a collection position positioned such that a portion of the sample collection port 540b receives a sample from the flow of material 580 and allows the material to pass through the sample receiving space 530 and onto the sample support surface 550. In this example, the sample collection tube 600 may be rotatable by a rotary actuator 650 coupled to the sample collection tube 600.

[0062] In some embodiments, the rotary actuator 650 may be configured to rotate the entire sample collection tube 600. In this embodiment, the rotary actuator 650 may rotate the sample collection tube 600 such that the sample collection port 540b is positioned to receive a sample from the flow of material 580 (e.g., a graphitized material). The sample collection tube 600 may be configured such that the material entering the sample collection port 540b flows into the sample receiving space 530 along the material flow axis (e.g., by gravity or any other physical or mechanical mechanism) and can only flow onto the sample support surface 550.

[0063] In some embodiments, the flow of material 580 moves in a first direction along the material flow axis, and at the collection position, the sample collection port 540 of the sample collection tube 600 is positioned upstream of the sample receiving space 530 of the body 520 along the material flow axis. For example, the material 580 can flow downward into the sample receiving space 530 by gravity. In one embodiment, the first direction is the downward direction and the material flow axis is the vertical axis. Thus, at the sample collection position, the sample collection port 540b of the sample collection tube 600 is positioned above the sample receiving space 530 of the body 520 along the vertical axis. In one embodiment, when the material 580 for sampling flows downward toward the sample collection tube 600, the sample collection port 540b of the sample collection tube 600 faces in the upward direction along the vertical axis. Generally, when a sample is collected, the rotational actuator 650 can return the sample collection tube 600 to the closed position so that material can no longer enter the sample collection port 540b.

[0064] In another embodiment, the rotational actuator 650 can be configured to rotate only the distal portion (not shown separately in FIG. 13) to return the sample collection tube 600 to the open or receiving position, while another portion of the sample collection tube proximal to the device body 520 (also not shown) remains stationary. Other embodiments are contemplated. For example, the sample collection tube 600 can remain stationary and any part of the sample collection ports 540(a, b) can be selectively opened and closed to allow the sample to move into the sample receiving space 530 and onto the sample support surface 550.

[0065] In a further embodiment, the device 500 may comprise a plunger 700 that is selectively movable within the sample receiving space 530. In one embodiment, the plunger 700 may define a sample support surface 550. In a further embodiment, the device 500 may further comprise a compression structure 720 located within the sample receiving space 530 of the body 520 between the plunger 700 and the fixed focal length optical alignment system 560, such that the compression structure 720 is selectively movable between an open position 725 and a closed position 730. In the closed position 730, the compression structure 720 is configured to cooperate with the plunger 700 to compress the sample when the plunger 700 advances towards the fixed focal length optical alignment system 560, without allowing passage of the sample. In some embodiments, the compression structure 720 may include an actuating block or a blind.

[0066] In a further embodiment, the body 520 may define a sample outlet port 800 that communicates with the sample receiving space 530. In other embodiments, the body 520 may define at least one sweep port (801a, 801b) positioned between the sample outlet port 800 and the fixed focal length optical alignment system 560. The at least one sweep port (801a, 801b) may be configured to receive gas flowing through the sample receiving space 530 and to cause the sample to exit the sample receiving space 530 through the sample outlet port 800. In another embodiment, the device may further comprise a shield structure positioned within the sample receiving space 530 of the body 520 between the plunger 700 and the fixed focal length optical alignment system 560. The shield structure may be selectively movable between an open position and a closed position, such that in the closed position, the shield structure is configured to direct gas entering the at least one sweep port (801a, 801b) towards the sample outlet port 800 without allowing passage of the sample.

[0067] As noted above, the graphite property evaluation device can be part of a system that includes the graphitization furnace or any suitable graphitization reactor described above. The sampling device can be configured such that the collection port of the sample device is positioned to receive a sample from the stream of material produced by the disclosed graphitization furnace or any suitable graphitization reactor. Specifically, it is contemplated that the reactor can be any embodiment of the disclosed gravity-feed reactor of the graphitization furnace.

[0068] Also described is a method that includes conducting a reaction within a reactor to produce a stream of material, such as a graphitized material, and receiving a sample from the stream of material within the sample collection port of the sampling device. In one embodiment, the reaction can be a graphitization reaction. In a further embodiment, the reactor can be the disclosed gravity-feed reactor of the graphitization furnace.

[0069] The features and advantages of the present disclosure are apparent from the detailed description, and the claims cover all such features and advantages. Many variations will occur to those skilled in the art, and any variations equivalent to those described in the present disclosure fall within the scope of the present disclosure. Those skilled in the art will understand that the concepts on which the present disclosure is based can be used as a basis for designing other methods and systems for carrying out some of the purposes of the present disclosure. As a result, the claims should not be regarded as limited by the description or examples.

Claims

1. A gravity-fed reactor, A supply structure configured to receive raw materials, Equipped with, The gravity-feed reactor comprises an inner tube defining the interior, a heating assembly circumferentially surrounding at least a portion of the inner tube, and an outer shell defining at least the lower portion of the gas path circumferentially surrounding the heating assembly. The heating assembly has at least one heating element configured to apply heat to the inner tube, The supply structure defines a raw material receiving space that communicates with the interior of the inner tube of the reactor, The interior of the inner tube of the reactor is fluidly isolated from the heating assembly and the gas path. A furnace characterized by the following features.

2. The inner tube has an upper portion that is not circumferentially surrounded by the heating assembly, The gas path surrounds at least a portion of the upper part of the inner tube in a circumferential direction. The furnace according to feature 1.

3. The supply structure comprises a housing and a raw material inlet defining the raw material receiving space, The housing surrounds the raw material inlet in the circumferential direction, The housing defines at least a portion of the upper part of the gas path. The furnace according to feature 1.

4. At least a portion of the upper part of the gas path is separated radially outward from the inner pipe and the raw material inlet. The furnace according to feature 3.

5. The housing has an inner surface, The raw material inlet has an outer surface, The furnace further comprises a gas receiving space defined between the inner surface of the housing and the outer surface of the raw material inlet, The gas receiving space is in fluid communication with the gas path. The furnace according to feature 3.

6. The at least one heating element includes at least one resistance heating element. The furnace according to feature 1.

7. The at least one heating element includes a plurality of heating elements positioned to circumferentially surround the at least portion of the inner tube. The furnace according to feature 1.

8. The aforementioned plurality of heating elements include four heating elements. The furnace according to feature 7.

9. The outer shell includes an insulating material, The insulating material is spaced radially outward from the inner pipe. The furnace according to feature 1.

10. The raw material inlet has a maximum inner diameter that is larger than the diameter of the inner tube. The furnace according to feature 3.

11. A raw material transfer system that is in fluid communication with the raw material receiving space of the supply structure. The furnace according to claim 1, further comprising the above.

12. The raw material transfer system has at least one valve configured to prevent air from entering the raw material receiving space. The furnace according to feature 11.

13. The raw material transfer system has a negative pressure source configured to discharge air from within the raw material transfer system. The furnace according to feature 12.

14. Aftercooler assembly configured to cool the material coming out of the inner tube of the reactor. The furnace according to claim 1, further comprising the above.

15. The aftercooler assembly has an inner tube that is in fluid communication with the inner tube of the reactor. The furnace according to feature 14.

16. The inner tube of the reactor extends along the length of the aftercooler assembly and the length of the inner tube. The furnace according to feature 14.

17. The aftercooler assembly further has an outlet. The furnace according to feature 14.

18. At least a portion of the outlet of the aftercooler assembly tapers as it moves downward to reduce the diameter of the outlet. The furnace according to feature 17.

19. The conveyor assembly that communicates with the outlet of the aftercooler assembly. The furnace according to claim 17, further comprising the above.

20. The conveyor assembly has a horizontal screw or an inclined screw. The furnace according to feature 19.

21. The screw is a mass flow screw. The furnace according to feature 20.

22. The mass flow screw is water-cooled. The furnace according to feature 21.

23. The screw has threads with a pitch that increases as it moves horizontally away from the reactor. The furnace according to feature 20.

24. The threads of the screw have a diameter that increases as they move horizontally away from the reactor. The furnace according to feature 23.

25. The thread of the screw has a maximum outer diameter, The conveyor assembly further comprises a conveyor housing in which the screw is housed. The conveyor housing has an inner diameter, The gap between the inner diameter of the conveyor housing and the maximum outer diameter of the screw is less than 20, 15, 12, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 square inch. The furnace according to feature 23.

26. The screw is a horizontal screw. The furnace according to feature 20.

27. The screw is inclined at an angle of less than 10 degrees. The furnace according to feature 20.

28. A first valve positioned between the outlet of the aftercooler assembly and the conveyor assembly. Furthermore, The first valve is configured to control the flow rate of material entering the conveyor assembly. The furnace according to feature 20.

29. The conveyor assembly has an outlet, The furnace further comprises a second valve configured to control the flow rate of material exiting the outlet of the conveyor assembly. The furnace according to feature 20.

30. The reactor has at least one temperature sensor, The furnace further comprises a controller which is communicatively coupled to the at least one temperature sensor of the reactor. The furnace according to feature 1.

31. The controller is configured to modify the operation of the reactor based on the temperature detected by the at least one temperature sensor of the reactor. The furnace according to feature 30.

32. The reactor further comprises a confocal Raman microscope configured to measure the properties of the material after the material has passed through the reactor. The controller is configured to receive an input indicating the measured properties of the material. The furnace according to feature 30.

33. The controller is configured to modify the operation of the furnace based on the measured properties of the material. The furnace according to feature 32.

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